€6 IOWA ACA.DEMY OF SCIENCES. 



were, however, sold at these figures. There are very large 

 quantities of ore in sight in these mines, as even a brief inspec- 

 tion clearly shows, and they are capable of yielding thousands 

 of tons for some years to come. 



The output of the mines for the past year can be given only 

 approximately. They have produced about 750,000 pounds of 

 lead and from 3,000 to 3,500 tons of zinc. But it must be 

 remembered that, as already stated, most of the zinc mines 

 were closed during the past season. They are easily capable 

 of yielding from 8,000 to 10,000 tons of ore annually. 



THE AREA OF SLATE NEAR NASHUA, N. H. 



BY J. L. TILTON. 



Maps of Crosby and Hitchcock. 

 The area briefly outlined. 

 Description of the slate area. 

 Description of the rocks. 



Section from Nashua northward. 



Section along the Massachusetts line. 



Section west of Hollis Center. 



Section east from Runnells Bridge, and southeast from Nashua. 

 Attempt to harmonize descriptions of Crosby and Hitchcock. 

 .Structure. 



Dip, strike, general section. 

 Evidences of faults. 

 Cause of metamorphism. 



Maps of Crosby and Hitchcock. — Crosby's map of eastern 

 Massachusetts represents an area of slate, or argillite, as it is 

 termed, running from Worcester through Lancaster and Pep- 

 perell^^to the New Hampshire state line. The eastern part of 

 this argillite, two and one-fourth miles wide on the map, but 

 four miles wide according to the text,* continues north into 

 New Hampshire just west of the Nashua river. On the east 

 of the argillite lies mica schist in an area very narrow (three- 

 fourths of a mile) near the state line, but much wider toward 

 the southern part of the township of Dunstable. On the west 



*Crosby's "Geology of Eastern Massachusetts," p. 137. 



